Previously known ways of creating and transferring pressure pulses through hydraulic fluid were disclosed by Taberner in U.S. Pat. No. 3,511,050, and in Russian Patents No. 120,128 and 1,242,205/23-26. Taberner discloses, in the drawings, an eccentric cam driving a piston with rectilinear motion to create a source of fluid pressure oscillations. The former Russian patent discloses a device for transferring the energy of a hydraulic shock to a piston functioning as the working hydraulic cylinder of a hammer. Hydraulic elastic shock waves are produced in a pipe which communicates with the hydraulic cylinder. However, the former Russian patent does not teach a new way to create the hydraulic shock wave. The later Russian patent discloses a device for creating stable pulsation utilizing a piston and cylinder arrangement driving an air cushion through a pressure line and into a liquid, thereby transferring the pulsed energy into the liquid. The air cushion functions to stabilize the pulsation of the liquid component. The piston is driven by a spinning wheel and connecting rod crank arm utilizing a variable length connecting rod to drive the piston. Although the combined wheel and crank assembly spin with a slight rotational mass imbalance due to the attached offset mass of the crank arm, the relatively small offset mass distribution of the wheel and crank arm will not produce significant vibratory imbalance and vibration displacement. In fact, application of machine design techniques to rotating objects produces balanced rotating objects which minimize or eliminate vibration. This invention proposes the opposite, to intentionally unbalance the mass and create large vibrations, then harness them into unidirectional oscillations with a rectilinear guideway, thereby creating strong vibrations and displacements at the mass by tuning the system to its natural excitation frequency or multiples of that.
The invention comprises a motor mounted on a movable carriage and which drives an unbalanced rotating mass, thereby creating inertial forces from the rotational imbalance of the mass which tends to shake the mass, motor and the associated mounting carriage due to the dynamic rotational imbalance. The carriage is constrained by a housing or body to shake about one translational axis, thereby imparting rectilinear motion to the carriage and a pair of first pistons rigidly fixed thereto. The first pistons are in direct communication with corresponding housing chambers completely filled with hydraulic fluid and, in response to push-pull action of the first pistons on the contained fluid, the drive fluid in turn acts upon, and produces rectilinear reciprocating motion of, a pair of second pistons and accompanying output shaft which are likewise fluid coupled to the associated housing chambers.
Objects, features and advantages of this invention are to provide a tunable apparatus and method for producing pressure oscillations in hydraulic fluid using the reaction forces produced by a rotating unbalanced mass to drive a pair of first pistons, and being in direct communication with hydraulic fluid, to transfer the oscillating pressure pulses to a pair of second pistons and correspondingly, a common output shaft, thereby acting on and doing work on an external system, utilizing the inertia forces created by the unbalanced rotating mass.